Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Kato, Tomoaki; Yamagishi, Isao
JAEA-Technology 2023-018, 53 Pages, 2023/11
JAEA-Technology-2023-018.pdf:2.6MB
In the decommissioning of Fukushima Daiichi Nuclear Power Station, radioactive carbonate slurry waste was generated using the Advanced Liquid Processing System (ALPS) pretreatment and temporarily stored in a high integrity container (HIC). In 2015, overflow of supernatant from HIC estimate as bubble retention in the carbonate slurry was discovered, increasing the need for a safety assessment of the carbonate slurry stored the HIC (HIC slurry). In this study, a carbonate slurry (simulated slurry) was prepared according to the Mg/Ca mass ratio in the ALPS inlet water of the HIC slurry which overflew the HIC. The effects of reaction time during the pretreatment process, suspended solids concentration (SS concentration), and settling time on the particle composition, morphology and rheological properties of the slurry were investigated. Evaluating the effect of reaction time and concentration process on chemical properties in slurry production, the effect of the reaction time was not confirmed in the simulated slurry that had undergone the concentration process, and slurry prepared at SS concentration of 150 g/L was composed of formless particles have a particle diameter of 0.4 
m or less. We also investigate the effect of SS concentration on sedimentability, decrease in SS concentration by dilution with processing solution contributed to an increase in the initial slurry settling velocity. Furthermore, two different flow characteristics were observed depending on the settling time, suggesting that the slurry at the initial settling time has non-Bingham flow properties, whereas it changes to Bingham flow properties as the settling time becomes longer. In addition, yield stress was increased with settling time, and this yield stress was found to be exponentially proportional to the density of the slurry. These results provide knowledge to estimate the current state of HIC slurry and are expected to contribute to the safety assessment.
Horita, Takuma; Yamagishi, Isao; Nagaishi, Ryuji; Kashiwaya, Ryunosuke*
JAEA-Technology 2021-012, 34 Pages, 2021/07
JAEA-Technology-2021-012.pdf:2.1MBJAEA-Technology-2021-012(errata).pdf:0.18MB
Waste mainly consisting of carbonate precipitates (carbonate slurry) from the Advanced Liquid Processing System (ALPS) and the improved ALPS at the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Holdings, Inc. have been storing in the High Integrity Container (HIC). The supernatant solution of carbonate slurry contained in some of HICs were overflowed in April of 2015. The all of level of liquid in the HICs were investigated; however, almost of the HICs were under the level of overflow. The mechanism of overflow suggested to be depending on the difference of the properties of the carbonate slurry such as the retention/release characteristics of the bubbles. Therefore, in order to clarify the mechanism of leakage, the repeatability experiment was carried out by using simulated carbonate slurry. The simulated carbonate slurry was perpetrated by using the same cross-flow filter system of the actual ALPS. Moreover, the preparative conditions for the simulated carbonate slurry were the same as Mg/Ca concentration ratio in inlet water of the ALPS (raw water) and the ALPS operating conditions. The chemical characteristics of simulated carbonate slurries were revealed by ICP-AES, pH meter, etc. The density of the settled slurry layer tended to increase depending on the calcium concentration in the raw water. The bubble injection test was conducted in order to investigate the bubble retention/release behavior in the simulated carbonate slurry layer. The simulated carbonate slurry with high settling density, which was generated by high calcium concentration solution was revealed to retain the injected bubbles. Since the ratio of concentration calcium and magnesium during the carbonate slurry generation is assumed to affect the retention of bubbles in the slurry layer, the information on the composition of raw water is one of important factor for overflow of HICs.
Sugita, Yutaka; Taniguchi, Naoki; Makino, Hitoshi; Kanamaru, Shinichiro*; Okumura, Taisei*
Nihon Genshiryoku Gakkai Wabun Rombunshi, 19(3), p.121 - 135, 2020/09
A series of structural analysis of disposal containers for direct disposal of spent fuel was carried out to provide preliminary estimates of the required pressure resistance thickness of the disposal container. Disposal containers were designed to contain either 2, 3 or 4 spent fuel assemblies in linear, triangular or square arrangements, respectively. The required pressure resistance thickness was evaluated using separation distance of the housing space for each spent fuel assembly as a key model parameter to obtain the required thickness of the body and then the lid of the disposal container. This work also provides additional analytical technical knowledge, such as the validity of the setting of the stress evaluation line and the effect of the model length on the analysis. These can then be referred to and used again in the future as a basis for conducting similar evaluations under different conditions or proceeding with more detailed evaluations.
Nakamura, Hisashi; Nakashima, Mikio
JAERI-Tech 2002-006, 58 Pages, 2002/03
JAERI-Tech-2002-006.pdf:2.56MB
Radiation exposure was estimated on production and utilization of recycled items using dismantling waste by assuming that their usage are restricted to nuclear facilities. The radiation exposure attributed to production of a steel-plate cast iron waste container, a receptacle for slag, and a drum reinforcement was calculated to be in the range of several Sv to several tens of Sv even in recycling contaminated metal waste of which radioactivity concentration of Co-60 is higher than the clearance level by a factor of two figures. It is also elucidated that casting of a multiple casting waste package meets the standards of dose equivalent rate for the transport of a radioactive package and the weight of the package will be able to kept around 20 tons for the convenience of the handling, in case of disposal of metal waste less than 37MBq/g with the steel-plate cast iron waste container. As the results, from the radiological exposure's point of view, it should be possible to use slightly contaminated metal for recycled items in waste management.
Nakamura, Hisashi; Hirabayashi, Takakuni; Akimoto, Jun*; Takahashi, Kenji*; Shindo, Hideaki; Sakurai, Daihachiro*; Almansour, A.*; Okane, Toshimitsu*; Umeda, Takateru*
Materials Science Forum, 329-330, p.441 - 448, 2000/00
no abstracts in English
Nakamura, Hisashi; Hirabayashi, Takakuni; Akimoto, Jun*; Takahashi, Kenji*; Shindo, Hideaki*; Sakurai, Daihachiro*; Almansour, A.*; Okane, Toshimitsu*; Umeda, Takateru*
Proceedings Modeling of Casting & Solidification Processes 4, 1999, p.437 - 445, 1999/09
no abstracts in English
Nakamura, Hisashi; Hirabayashi, Takakuni; Akimoto, Jun*; Takahashi, Kenji*; Shindo, Hideaki*; Sakurai, Daihachiro*; Almansour, A.*; Okane, Toshimitsu*; Umeda, Takateru*
Int. J.Cast Metals Res., 11(5), p.339 - 343, 1999/00
Times Cited Count：0 Percentile：0.01(Metallurgy & Metallurgical Engineering)no abstracts in English
Nakamura, Hisashi; Hirabayashi, Takakuni
Nihon Kikai Gakkai Dai-6-Kai Doryoku, Enerugi Gijutsu Shimpojiumu '98 Koen Rombunshu, p.371 - 376, 1998/00
no abstracts in English
Okoshi, Minoru; Abe, Masayoshi; Yoshimori, Michiro; Sakai, Akihiro
Proc. of Waste Management'98 (CD-ROM), 5 Pages, 1998/00
no abstracts in English
; *;
Nihon Genshiryoku Gakkai-Shi, 23(5), p.338 - 341, 1981/00
Times Cited Count：0 Percentile：0.02(Nuclear Science & Technology)no abstracts in English
-ray irradiationIdesaki, Akira*; Barr, L.; Taguchi, Mitsumasa*; Yamaguchi, Tetsuji
no journal, ,
Because 1F water treatment secondary waste slurry is stored in a high-performance polyethylene container, it is necessary to understand radiation degradation of polyethylene. In particular, this study was conducted because there is no knowledge about the influence of water or slurry. Stress cracking properties, one of the indicators of degradation of polyethylene, were different in air and in water (and in slurry). This difference was considered together with the results of other characteristic tests. In addition, it was revealed that degradation is effectively suppressed in any environment by containing an antioxidant in polyethylene.
